In overlaying hot drape composite laminate material onto a three dimensional form in fabricating three dimensional parts, it is a difficult and problematic to reduce fiber wrinkling within plies of composite laminate material. Each three dimensional part has a unique configuration such that ply wrinkling is often unknown until trial parts are made. As fibers in a ply extend over a contour in the three dimensional forming tool the fibers tend to wrinkle. Wrinkling of the fibers is not desired since wrinkling diminishes the strength performance of the finished composite part.
Fibers tend to wrinkle more so with steeper ramp ratios employed in fabricating a composite part. Complications can be presented to a designer and manufacturer where a contour to the part to be assembled is needed for transitioning the shape of a particular part wherein the distance or run in which to accomplish the ramping or transitioning is limited. A steeper ramping or contour tends to promote wrinkling of the fibers within the plies of that part of the assembly. As a result, a less steep and shallower ramp ratio may be needed to reduce the undesired fiber wrinkling in fabrication, thereby affecting the overall design of the assembly being built. Design adjustments needed based on using shallower contours present complications for the designer of the assembly and result in additional costs.
In other instances, fabricators may select steeper contours and use more plies in constructing a particular composite laminated part in an attempt to counter the effect of fibers that will wrinkle in the part fabrication process. Designers may also use additional fibers or fiber configurations within the plies of the laminate composite material such as a fabric configuration in attempts to also counter the undesired strength performance of fiber wrinkling. These fabricating strategies lead to more expense in fabricating the part and cause the part to become heavier in weight.
There is a need for a method for reducing and eliminating the occurrence of wrinkling of fibers within the composite laminate material used in forming hot drape three dimensional components with a three dimensional forming tool wherein the three dimensional forming tool includes ramping or contoured sides. The method would need to permit the designer to use greater or steeper ramp ratios for a contour for component parts and provide the designer greater flexibility in designing of the composite part and its associated assembly, such as, for example, in fabricating an aircraft. The method would also need to prevent a need to add plies in an attempt to compensate for a drop in strength of the part with the occurrence of wrinkled fibers in the fabrication of the part. The addition of plies also adds unwanted weight to the fabricated part. Similarly, the method would need to reduce the occurrence of incorporating additional fibers or employing a fabric configuration to similarly attempt to compensate for a drop in strength of the part with the occurrence of wrinkled fibers in the fabrication of the part.